Web and Developer Tools

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NoScript Security Suite Featured

The best security you can get in a web browser!
Allow active content to run only from sites you trust, and protect yourself against XSS and Clickjacking attacks.

Rated 5 out of 5 stars (1,574)
65,433 weekly downloads

Stylish

Restyle the web with Stylish, a user styles manager. Stylish lets you easily install themes and skins for Google, Facebook, YouTube, Tumblr, and many, many other sites. You can even customize Firefox and other programs themselves.

Rated 4 out of 5 stars (814)
23,387 weekly downloads

User Agent Switcher

The User Agent Switcher extension adds a menu and a toolbar button to switch the user agent of a browser.

Rated 4 out of 5 stars (262)
23,176 weekly downloads

FoxyProxy Standard

FoxyProxy is an advanced proxy management tool that completely replaces Firefox's limited proxying capabilities. For a simpler tool and less advanced configuration options, please use FoxyProxy Basic.

Rated 4 out of 5 stars (355)
20,046 weekly downloads

Web Developer

The Web Developer extension adds various web developer tools to the browser.

Rated 5 out of 5 stars (230)
15,871 weekly downloads

Element Hiding Helper for Adblock Plus No Restart

Fight the text ads! Element Hiding Helper is a companion extension for Adblock Plus meant to make creating element hiding rules easier.

Rated 5 out of 5 stars (450)
14,616 weekly downloads

Full Web Page Screenshots (♥♥♥♥♥)

FireShot makes full web page screenshots. Demo: http://bit.ly/RlBQMV

Screenshots can be quickly captured and:

― Saved as Image or PDF
― Sent to clipboard
― Printed
― Annotated *
― Uploaded *
― E-Mailed *

* OS Windows only

Rated 5 out of 5 stars (451)
13,854 weekly downloads

SQLite Manager

Manage any SQLite database on your computer.

Rated 5 out of 5 stars (47)
13,313 weekly downloads

Flagfox No Restart

Displays a country flag depicting the location of the current website's server and provides a multitude of tools such as site safety checks, whois, translation, similar sites, validation, URL shortening, and more...

Rated 5 out of 5 stars (652)
13,160 weekly downloads

JavaScript Debugger

As of Firefox 33, Venkman *no longer works*, as the APIs which it needs have been removed.

Venkman is the code name for Mozilla's JavaScript Debugger. Venkman aimed to provide a powerful JavaScript debugging environment for Mozilla based browsers.

Rated 4 out of 5 stars (50)
6,975 weekly downloads

Live HTTP Headers

View HTTP headers of a page and while browsing.

Rated 4 out of 5 stars (168)
5,836 weekly downloads

Screengrab (fix version)

Screengrab! saves webpages as images.
0.99 released!
New features: upload to internet

Rated 5 out of 5 stars (286)
5,557 weekly downloads

HttpFox

An HTTP analyzer addon for Firefox

Rated 4 out of 5 stars (166)
4,412 weekly downloads

Tiny JavaScript Debugger

TinyJSD is a JavaScript debugger for privileged code running Mozilla products like Firefox, Thunderbird, SeaMonkey. It serves to debug the application as well as extensions written in JavaScript.

Rated 4 out of 5 stars (6)
2,819 weekly downloads

Remote XUL Manager No Restart

Manages the Remote XUL whitelist to allow websites and local files to load XUL content. For versions compatible with Firefox 41 and lower, see All Versions page below.

Rated 5 out of 5 stars (36)
2,299 weekly downloads

WorldIP - Geo Add-on with Security Features

Professional Geo Add-on with security features and advanced network tools. Anti-phishing. Protection against DNS spoofing and fake sites. All DNS records for domain. The real location of web server, country flag, extended information about datacenter

Rated 5 out of 5 stars (119)
2,286 weekly downloads

FoxyProxy Basic

FoxyProxy Basic is a simple on/off proxy switcher. More advanced features and configuration options are offered by FoxyProxy Standard.

Rated 4 out of 5 stars (31)
2,237 weekly downloads

RefControl

Control what gets sent as the HTTP Referer on a per-site basis.

Rated 4 out of 5 stars (184)
2,237 weekly downloads

about:addons-memory 2016 No Restart

Adds a new page that shows add-on memory usage

Rated 5 out of 5 stars (12)
2,224 weekly downloads

Font Finder

FontFinder is created for designers, developers and typographers. It allows a user to analyze the font information of any element on a page, copy any piece(s) of that information to the clipboard, and perform inline replacements to test new layouts.

Rated 4 out of 5 stars (69)
2,155 weekly downloads